"I think Fermi also had the unreasonable assumption that interstellar aliens would figure out how to get past the speed of light..."
The Fermi Paradox does not involve faster-than-light travel.
"We still have this problem of what DNA was doing for that approximately two and a half billion years—the overwhelming majority of the history of life on Earth. Why didn’t it evolve at all during that time? What’s going on?"
In the evolution of life there are events that appear to be difficult, and events that appear to be easy:
1. The creation of life seems to be easy as the first life appeared very close to earth formation, in a very hostile environment (unless that seeding of life was done intentionally).
2. Sexual reproduction seems hard - it took 2.5B years to evolve, despite the significant evolutionary advantage
3. Plants and animal seem hard again - it took another billion years after sexual reproduction.
After plants and animals appeared, things seemed to accelerate, so for example you could say that having an intelligent species take over the world seems inevitable.
The problem is that those timescales are getting close to the entire lifespan of earth. Within a few hundred million years we expect the oceans to boil and all life to die. So even on earth, with a single sample, it appears that we are incredibly lucky to reach where we reached.
What's the mechanism for boiling oceans? I thought the Sun was a few billion years away from going red giant.
Personally, if I had to bet on an early filter, I'd go for the eukaryotic transition. Not so much the "having a nucleus" part, more the "dealing with genes at scale" part, because it requires so much machinery so low in the stack with so many knock-on effects and such a long payoff horizon. It's like the single-thread to multi-thread transition, except instead of everyone agreeing that multi-thread was the future and merely struggling to get there, we instead had a situation where everyone was trying to eat (literally, as in cannibalize) the proponents of multi-thread if their programs failed to go faster per dollar of hardware.
Speed of light is a problem in that it makes a lot journeys essentially one-way.
If we're talking about manned-space travel, the acceleration needed to get to anything approaching the speed of light would itself take months, if not an entire year.
So that's two years of travel just accelerating and braking. And to the next nearest star, you will probably be traveling at speed for somewhere around 3 years. I'm just assuming that you'd travel half a light year accelerating and braking. It's likely wrong. But I also suspect it's generous.
That's 10 years round trip to get to our closest neighbor.
And yes, while time dilation would cause those on the vessel to experience far less time than that, the people on Earth will still experience every minute of those ten years. It's also about 9 years before you even get a message. Because at least the information can be sent at SOL without having to worry about killing the messenger. 5 years to get there, 4 years to send a message back.
And some people will say "well, what about Von Neumann probes". Well, that still has the problem of at least a decade long wait to see if you have any return on that investment. And it assumes that we can develop artificial intelligence to the degree that such probes are possible. Which is a big leap considering we don't even really know what intelligence or conscience even is. We know what it can do, but we don't know how either works.
So, in order to colonize the galaxy, a civilization needs to be able to dedicate enormous resources to projects where the potential payoff, if any, are going to be at least a decade away. And to have developed technology far surpassing anything we have at the current moment. To have figured out very fundamental questions about exactly what life is.
Yeah. I'm not surprised we haven't seen any extraterrestrial life. The universe is simply too vast.
The rocket equation,the difference between momentum change (linear) and energy (quadratic) in Vexhaust of rockets, and the laws of thermodynamics constrain us to low speeds if we actually want to stop anywhere rather than sail by in a few seconds, which doesn't get you much more than good telescopes do, if anything. Slow travel is also a lot safer because of kinetic energy being quadratic in v.
If a vessel can be made that survives travel durations of thousands of years, and the passengers likewise, then they're adapted for life in interstellar space, and won't see much point in expending a lot of energy to go far down a gravity well to a hostile environment. Telescopes are fine for observation. There's plenty of stuff in Kuiper belts. The locals won't be interesting until they get out to their own Kuiper belt anyway.
The Fermi paradox is obviously influenced by how easy (and fast) it is to get from planet to planet, and Fermi himself did wonder about the probability of faster-than-light travel. From the Wikipedia page on the subject:
> Although he was not the first to consider this question, Fermi's name is associated with the paradox because of a casual conversation in the summer of 1950 with fellow physicists Edward Teller, Herbert York and Emil Konopinski. While walking to lunch, the men discussed recent UFO reports and the possibility of faster-than-light travel. The conversation moved on to other topics, until during lunch Fermi allegedly said suddenly, "But where is everybody?" (although the exact quote is uncertain)
I'm not an astrophysicist, so somebody correct me if I'm wrong.
My understanding is that due to the expansion of the universe, all the galaxies are moving away from each other. The rate at which they move away from each other is directly proportional to the distance between them (the Hubble Constant), because space itself is expanding. Kind of like if you lined up a bunch of deflated balloons next to each other and inflated them at the same rate.
At some point, around 13-15 billion light years away, galaxies are actually moving away from us faster than the speed of light. Also, because their "velocity" is proportional to the distance, they're actually accelerating away from us.
With each year, more things reach a "velocity" where they're moving away from us faster than the speed of light, and will never be reachable without faster than light travel.
Thus the Fermi Paradox only makes sense if you consider it likely that interstellar aliens could travel faster than the speed of light. If FTL travel is impossible, then a timer was started on the day the universe was created, counting down the seconds until our galaxies were moving away from each other too fast for contact to ever be possible. In that case, the Fermi Paradox is a paradox no more. It's entirely possible other life does exist, it's just physically impossible for us to contact each other.
The Fermi Paradox was proposed during a discussion about whether faster-than-light travel would be developed. Fermi, famously, exclaimed "where are they?" saying that if ftl travel is possible, we should be regularly visited by the numerous alien civilizations that must, statistically, be out there.
The Fermi Paradox has come to be the term describing the more general lack of alien detection, but it's only a "paradox" if we expect to be able to detect aliens. That expectation is only reasonable if aliens produce enough activity close enough to us that we would be able to observe it. If FTL is possible, that assumption is an unequivocal yes. Without FTL, it's infinitely more contentious.
Light is only slow relative to human timescales. It's wicked fast on evolutionary timescales.
Even accounting for sublight speeds and conservative spreading assumptions, galactic colonization should only take millions of years, not billions. Evolution has taken billions of years. So if an alien civilization in our galaxy got a billion year headstart -- which would be an unremarkable change to the evolutionary timeline -- then they should already have colonized the galaxy. They should be everywhere, and we should see them, but we don't.
Life has existed on Earth for almost a third of the lifetime of the universe as far as we can tell. This doesn't leave that much room for older civilizations, especially if it happens that life on Earth was especially fast evolving.
I don't think it's accurate to say that light is slow on any timescale. It's literally the fastest thing, no matter what scale you're on.
The issue at hand, and the reason that we can make light look slow, is that we can't comprehend the distances we're talking about covering. No one said anything about restricting the search for life to our galaxy, so let's set that aside. Given the distances involved, the odds that evolution has gone complex in more than one galaxy are high, but the odds that we might find evidence of this are low.
But intelligent civilizations don't exist on evolutionary timescales, they exist on the timescales of intelligent beings, like us. We struggle to maintain projects for more than a few years, a tiny fraction of our lifetimes. Our oldest institutions are only a few thousand years old, dozens of generations. Many of our civilizations rose and fell within centuries. Our species is much less than a million years old, and while it is unclear how long we will last, it seems pretty optimistic to think we are in the first few percent of our species history, nonetheless the first few thousandths of a percent of our civilization's history. If we had built ships travelling at 1% of lightspeed to colonize the galaxy, and launched them when the common ancestor of humans and chimps lived, some of them would still be travelling to their destinations. Maybe there are rare species that live on timescales tens, hundreds, even thousands of times longer than ours, but even for them these would be long time periods.
And it's not enough to simply reach these distant star systems, you need to survive there indefinitely. A billion years is a long time, much longer than complex life has existed on Earth. Most of Earth's crust is less than 250 million years old. Objects in space would be pulverized to dust by a billion years of collisions, assuming their orbits were even stable for anywhere near that long. On timescales like that, even structures made of solid granite would erode away on a planet's surface. Maybe by looking for weird minerals which couldn't have formed naturally or microfragments of broken down structures we could identify a civilization as having existed in the deep geologic past, but there is no way we could do that sort of analysis from light years away, even if we knew what to look for.
Realistically, there are only a few technosignatures we could hope to find. Of course there are active radio transmissions, which requires the civilization to be active in an incredibly narrow timeframe. Exoplanet atmospheres containing short lived gases with no known natural production mechanism would be good, and may outlive a civilization, but anything stable enough to last for geologic timescales would be impossible to rule out as natural. Probably the longest lived evidence that we could detect would be the remnants of alien megastructures in space. No one really knows how long say a dyson sphere would last after it stops being maintained, maybe millions of years. But unless we make some extremely tenuous assumptions about what and how alien civilizations would construct megastructures, we can only make extremely rough guesses as to what a functional megastructure would look like, nonetheless one that has suffered millions of years of wear and tear. Of course eventually they'll all start to look like clouds of dust and debris, but how do we distinguish them from the clouds of dust and debris that we find all over the place with a presumed natural origin?
I recently have been considering whether space travel is even relevant to advanced species.
Assuming the technological knowhow for interstellar travel requires much more evolution and adaptation I wonder if at that point we or any species would be interested in physically travelling.
Early scientific research was mostly based on field observations due to the lack of intricate technological understanding. As we advance, more and more of our research is done in labs and on computers for obvious reasons. I doubt aliens or our future selves will be reliant on field observations for research.
The ocean is on our doorstep, yet vast amounts of research have not gone into exploring that compared to space. The reason is because of the perceived potential outcomes of space vs ocean exploration. The same reasons will stop us from exploring physical space in the future, and could be preventing aliens from exploring now.
Eventually a matrix like integration with technology could give ourselves access to realities with enough to keep our minds occupied. Not only could we have access to procedurally generated worlds, but procedurally generated physics and rules to those worlds. Once we crack the locks to access the rules our consciousness we can generate even more "realities" to explore. Natural evolution of the mind could negate the need for the technological matrix.
I consider the mind to be the end game for exploration. The "last frontier" if you will. Negating the need for physical travel. Consider as an example the Organian way of life from Star Trek.
I completely agree. This seems to be the most convincing solution to the Fermi Paradox. The physical world seems so limited and boring compared to what a virtual world could be (as you said, at least if we ever crack the secret of consciousness) that it seems self-evident that any sentient beings would eventually prefer to "live" inside that, removing itself from the physical world almost entirely (leaving behind just probes to collect energy and repair themselves and the computers generating their new reality, I guess).
There's a song by one of my favorite artists, Peter Mulvey, which touches on this point. It's more of a spoken word poem, titled "Vlad the Astrophysicist". In the song, Peter asks Vlad if there are aliens, and if there are, why haven't they contacted us? Vlad answers basically that there almost certainly are aliens, but civilizations don't last for long enough compared to the size of the universe.
> "You see?" He said, "They never meet each other. Time is too long, space is too large.
I mean sure, maybe at one time, right next to each other at the same time, fss, fss -
Two civilizations sprang up and they had war, better yet they had peace,
They had arts exchanges, they had an intergalactic library... but they are all dead now, too.
In all likelihood, we are alone, and by the time the next civilization arises,
We'll have been gone for a long, long time."
Fermi did not think that aliens would get past the speed of light, but what we have found out in the last 40 years does make his paradox less striking. If Fermi was alive today I expect he would not have wondered "where's everyone?" Instead I think that he would be saying that there's a range of reasons why intelligent life is vanishingly rare. The dynamics of most solar systems (big planets migrate in) and the role of Jupiter as a comet catcher as well as the insights into the history of life and the miracle of the eucaryotic cell.
I recall waiting for Shoemaker-Levy 9 [0] back in 1992; it was not expected to go off with such a bang, when it did it put the spotlight on Jupiter's protective effect.
I didn't read the book, but at least in this article/interview they use too many[1] qualitative descriptors like "quite rare", "incredibly vast", "too far", "a lot longer", "long before", "very big", and "almost entirely empty". The quantities involved are not intuitive, you need to run a calculator to figure out the probability.
The Grabby Aliens hypothesis [2] [3] is a recent publication by Robin Hanson (originator of the descriptor "The Great Filter" in the Fermi Paradox) which describes these times and distances mathematically.
In short, either the model and its assumptions are flawed, or we're really, really early as far as intelligent spacefaring alien species go. We're here about 13.8 billion years after the Big Bang, and the solar system about 4.6 billion years old. That's nothing in terms of spacetime! Expanding at 0.1c (note, this all assumes non-faster-than-light travel) we could recolor the spectrum of the Milky Way in 1 million years, Andromeda in 25 million years, and the entire local group in 50 million years. None of those galaxies are 'just too far away'.
[1]: 9, by my count, and only 1 quantitative descriptor - 2.5 billion years.
The Earth may be rare but self perpetuating intelligent systems may not be.
The chaotic fluid dynamics of some gas giant, star, or accretion disk could spontaneously form an intelligence given enough time the same way we evolved from a chaotic system here on Earth.
There must be something like the Drake equation but for how many large chaotic systems need to exist for something to evolve that can perform non-trivial computation.
Like an estimate for how many Solaris planets may exist in the universe.
My fun hypothesis is that it's relatively easy for technology to trigger https://en.wikipedia.org/wiki/False_vacuum_decay, which results in a bubble of destruction expanding outward at the speed of light. The universe actually looks like swiss cheese, but we're still here because c is so slow.
Readit News
The Fermi Paradox does not involve faster-than-light travel.
"We still have this problem of what DNA was doing for that approximately two and a half billion years—the overwhelming majority of the history of life on Earth. Why didn’t it evolve at all during that time? What’s going on?"
Those early single-cell organisms were evolving!
1. The creation of life seems to be easy as the first life appeared very close to earth formation, in a very hostile environment (unless that seeding of life was done intentionally).
2. Sexual reproduction seems hard - it took 2.5B years to evolve, despite the significant evolutionary advantage
3. Plants and animal seem hard again - it took another billion years after sexual reproduction.
After plants and animals appeared, things seemed to accelerate, so for example you could say that having an intelligent species take over the world seems inevitable.
The problem is that those timescales are getting close to the entire lifespan of earth. Within a few hundred million years we expect the oceans to boil and all life to die. So even on earth, with a single sample, it appears that we are incredibly lucky to reach where we reached.
Personally, if I had to bet on an early filter, I'd go for the eukaryotic transition. Not so much the "having a nucleus" part, more the "dealing with genes at scale" part, because it requires so much machinery so low in the stack with so many knock-on effects and such a long payoff horizon. It's like the single-thread to multi-thread transition, except instead of everyone agreeing that multi-thread was the future and merely struggling to get there, we instead had a situation where everyone was trying to eat (literally, as in cannibalize) the proponents of multi-thread if their programs failed to go faster per dollar of hardware.
If we're talking about manned-space travel, the acceleration needed to get to anything approaching the speed of light would itself take months, if not an entire year.
So that's two years of travel just accelerating and braking. And to the next nearest star, you will probably be traveling at speed for somewhere around 3 years. I'm just assuming that you'd travel half a light year accelerating and braking. It's likely wrong. But I also suspect it's generous.
That's 10 years round trip to get to our closest neighbor.
And yes, while time dilation would cause those on the vessel to experience far less time than that, the people on Earth will still experience every minute of those ten years. It's also about 9 years before you even get a message. Because at least the information can be sent at SOL without having to worry about killing the messenger. 5 years to get there, 4 years to send a message back.
And some people will say "well, what about Von Neumann probes". Well, that still has the problem of at least a decade long wait to see if you have any return on that investment. And it assumes that we can develop artificial intelligence to the degree that such probes are possible. Which is a big leap considering we don't even really know what intelligence or conscience even is. We know what it can do, but we don't know how either works.
So, in order to colonize the galaxy, a civilization needs to be able to dedicate enormous resources to projects where the potential payoff, if any, are going to be at least a decade away. And to have developed technology far surpassing anything we have at the current moment. To have figured out very fundamental questions about exactly what life is.
Yeah. I'm not surprised we haven't seen any extraterrestrial life. The universe is simply too vast.
If a vessel can be made that survives travel durations of thousands of years, and the passengers likewise, then they're adapted for life in interstellar space, and won't see much point in expending a lot of energy to go far down a gravity well to a hostile environment. Telescopes are fine for observation. There's plenty of stuff in Kuiper belts. The locals won't be interesting until they get out to their own Kuiper belt anyway.
> Although he was not the first to consider this question, Fermi's name is associated with the paradox because of a casual conversation in the summer of 1950 with fellow physicists Edward Teller, Herbert York and Emil Konopinski. While walking to lunch, the men discussed recent UFO reports and the possibility of faster-than-light travel. The conversation moved on to other topics, until during lunch Fermi allegedly said suddenly, "But where is everybody?" (although the exact quote is uncertain)
My understanding is that due to the expansion of the universe, all the galaxies are moving away from each other. The rate at which they move away from each other is directly proportional to the distance between them (the Hubble Constant), because space itself is expanding. Kind of like if you lined up a bunch of deflated balloons next to each other and inflated them at the same rate.
At some point, around 13-15 billion light years away, galaxies are actually moving away from us faster than the speed of light. Also, because their "velocity" is proportional to the distance, they're actually accelerating away from us.
With each year, more things reach a "velocity" where they're moving away from us faster than the speed of light, and will never be reachable without faster than light travel.
Thus the Fermi Paradox only makes sense if you consider it likely that interstellar aliens could travel faster than the speed of light. If FTL travel is impossible, then a timer was started on the day the universe was created, counting down the seconds until our galaxies were moving away from each other too fast for contact to ever be possible. In that case, the Fermi Paradox is a paradox no more. It's entirely possible other life does exist, it's just physically impossible for us to contact each other.
The Fermi Paradox has come to be the term describing the more general lack of alien detection, but it's only a "paradox" if we expect to be able to detect aliens. That expectation is only reasonable if aliens produce enough activity close enough to us that we would be able to observe it. If FTL is possible, that assumption is an unequivocal yes. Without FTL, it's infinitely more contentious.
Fermi Paradox? There's yer problem right there: https://preview.redd.it/w67ihk0r2ly71.gif?format=mp4&s=4611c...
Even accounting for sublight speeds and conservative spreading assumptions, galactic colonization should only take millions of years, not billions. Evolution has taken billions of years. So if an alien civilization in our galaxy got a billion year headstart -- which would be an unremarkable change to the evolutionary timeline -- then they should already have colonized the galaxy. They should be everywhere, and we should see them, but we don't.
The issue at hand, and the reason that we can make light look slow, is that we can't comprehend the distances we're talking about covering. No one said anything about restricting the search for life to our galaxy, so let's set that aside. Given the distances involved, the odds that evolution has gone complex in more than one galaxy are high, but the odds that we might find evidence of this are low.
And it's not enough to simply reach these distant star systems, you need to survive there indefinitely. A billion years is a long time, much longer than complex life has existed on Earth. Most of Earth's crust is less than 250 million years old. Objects in space would be pulverized to dust by a billion years of collisions, assuming their orbits were even stable for anywhere near that long. On timescales like that, even structures made of solid granite would erode away on a planet's surface. Maybe by looking for weird minerals which couldn't have formed naturally or microfragments of broken down structures we could identify a civilization as having existed in the deep geologic past, but there is no way we could do that sort of analysis from light years away, even if we knew what to look for.
Realistically, there are only a few technosignatures we could hope to find. Of course there are active radio transmissions, which requires the civilization to be active in an incredibly narrow timeframe. Exoplanet atmospheres containing short lived gases with no known natural production mechanism would be good, and may outlive a civilization, but anything stable enough to last for geologic timescales would be impossible to rule out as natural. Probably the longest lived evidence that we could detect would be the remnants of alien megastructures in space. No one really knows how long say a dyson sphere would last after it stops being maintained, maybe millions of years. But unless we make some extremely tenuous assumptions about what and how alien civilizations would construct megastructures, we can only make extremely rough guesses as to what a functional megastructure would look like, nonetheless one that has suffered millions of years of wear and tear. Of course eventually they'll all start to look like clouds of dust and debris, but how do we distinguish them from the clouds of dust and debris that we find all over the place with a presumed natural origin?
Assuming the technological knowhow for interstellar travel requires much more evolution and adaptation I wonder if at that point we or any species would be interested in physically travelling.
Early scientific research was mostly based on field observations due to the lack of intricate technological understanding. As we advance, more and more of our research is done in labs and on computers for obvious reasons. I doubt aliens or our future selves will be reliant on field observations for research.
The ocean is on our doorstep, yet vast amounts of research have not gone into exploring that compared to space. The reason is because of the perceived potential outcomes of space vs ocean exploration. The same reasons will stop us from exploring physical space in the future, and could be preventing aliens from exploring now.
Eventually a matrix like integration with technology could give ourselves access to realities with enough to keep our minds occupied. Not only could we have access to procedurally generated worlds, but procedurally generated physics and rules to those worlds. Once we crack the locks to access the rules our consciousness we can generate even more "realities" to explore. Natural evolution of the mind could negate the need for the technological matrix.
I consider the mind to be the end game for exploration. The "last frontier" if you will. Negating the need for physical travel. Consider as an example the Organian way of life from Star Trek.
> "You see?" He said, "They never meet each other. Time is too long, space is too large. I mean sure, maybe at one time, right next to each other at the same time, fss, fss - Two civilizations sprang up and they had war, better yet they had peace, They had arts exchanges, they had an intergalactic library... but they are all dead now, too. In all likelihood, we are alone, and by the time the next civilization arises, We'll have been gone for a long, long time."
https://www.youtube.com/watch?v=o9kbcGfX35M
Do you happen to have any info on this?
Attempting to answer my own question, I found https://earthsky.org/space/is-it-true-that-jupiter-protects-... and also https://bigthink.com/hard-science/how-jupiter-protects-earth... but I was curious if you knew of better sources to read up on it.
[0] https://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9
The Grabby Aliens hypothesis [2] [3] is a recent publication by Robin Hanson (originator of the descriptor "The Great Filter" in the Fermi Paradox) which describes these times and distances mathematically.
In short, either the model and its assumptions are flawed, or we're really, really early as far as intelligent spacefaring alien species go. We're here about 13.8 billion years after the Big Bang, and the solar system about 4.6 billion years old. That's nothing in terms of spacetime! Expanding at 0.1c (note, this all assumes non-faster-than-light travel) we could recolor the spectrum of the Milky Way in 1 million years, Andromeda in 25 million years, and the entire local group in 50 million years. None of those galaxies are 'just too far away'.
[1]: 9, by my count, and only 1 quantitative descriptor - 2.5 billion years.
[2]: https://grabbyaliens.com/
[3]: A nice video summary - https://www.youtube.com/watch?v=LceY7nhi6j4
The chaotic fluid dynamics of some gas giant, star, or accretion disk could spontaneously form an intelligence given enough time the same way we evolved from a chaotic system here on Earth.
There must be something like the Drake equation but for how many large chaotic systems need to exist for something to evolve that can perform non-trivial computation.
Like an estimate for how many Solaris planets may exist in the universe.